The present disclosure relates, generally, to magnetostrictive resonators and, more particularly, to systems for characterizing the resonance behavior of magnetostrictive resonators. It will be appreciated by those of skill in the art that magnetostrictive resonators are also sometimes referred to as magnetoelastic resonators, and the present disclosure will refer to both types of devices as “magnetostrictive resonators,” or simply “resonators.”
Biosensor systems may be used to detect and/or measure the presence of a wide variety of biological species (e.g., pathogenic bacteria and viruses that are widely found in food, soil, and water). A typical biosensor system comprises of three parts: (1) a sensing element, (2) a sensor platform, and (3) an interrogation system. The sensing element (e.g., antibody, phage, etcetera) may react with a target species in a sample due to its biomolecular recognition properties, which results in a physical and/or chemical change in the sensing element. As the change in the sensing element is usually not observable by direct human visualization, the sensor platform is utilized to detect and/or measure this change. In other words, the sensor platform converts the physical and/or chemical change in the sensing element into an output signal (e.g., an electromagnetic signal). The interrogation system is used to measure the output signal of the sensor platform (and often performs signal amplification, processing, and display, among other operations). Such biosensor systems may offer many advantages, such as sensitivity, ease of operation, and fast detection, making biosensor systems an excellent candidate for in-the-field detection and/or monitoring.
Various types of sensor platforms have been investigated in the development of high-performance biosensor systems, such as acoustic wave devices and optical fiber devices. Among the acoustic wave devices, magnetostrictive resonators provide many advantages. For instance, one advantage of magnetostrictive resonators over other acoustic wave devices is that magnetostrictive resonators may be wirelessly interrogated. When a magnetic field is applied to a magnetostrictive resonator, the shape of the resonator will change depending on the magnetic field. If a time-varying magnetic field is applied, a vibration will be introduced in the magnetostrictive resonator. The magnetostrictive resonator then generates its own time-varying magnetic field, which may be wirelessly measured. When coupled with one or more sensing elements, a magnetostrictive resonator may operate as a mass sensor because its resonance frequency will change with a mass load. In such embodiments, the resonance frequency of the magnetostrictive resonator serves as the output signal of the sensing platform. For high-performance biosensor systems to fully utilize the advantages of magnetostrictive resonators as sensing platforms, appropriate interrogation systems are needed.